Sensor size of the Xsi Chip is 14.8 mm x 22.2 mm, with a 3 x 2 aspect ratio and a 1.6 focal multiplier. In other words a 1000mm scope provides the focal length of a 1600mm scope. Hope this helps. Bob -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Canopus56 Sent: Thursday, May 05, 2011 11:56 PM To: Utah Astronomy List Serv Subject: [Utah-astronomy] Canon Xsi 450D CCD well dimensions - what are Some misc questions on the Canon XSi 450 DSLR for astrophotography: What are the dimensions of (1) the CMOS sensor and (2) an individual well on a Canon XSi 450D? (3) What is the sensor id used in this camera? (4) With respect to the sensor cleaning function, exactly what is that and how does it work? Assuming that the feature somehow shakes the dust of the chip, do you have to take the lens out really have the sensor cleaned? If you leave the lens in, does the cleaning feature just make the dust float around in the camera because it has no way to exit the body? Thanks, Kurt _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php